A memory device of three-dimensional structure has been proposed. The memory device includes a stacked body including a plurality of electrode layers being stacked between insulating layers. A charge storage film and a semiconductor film are provided in the stacked body, and extend in a stacking direction of the stacked body.
Tungsten and molybdenum are studied as a material of the electrode layer of such a three-dimensional memory device. Tungsten and molybdenum may contain boron in film formation. In a following heat treatment process, the boron is diffused to the insulating layer near the electrode layer, which may cause a deterioration in the characteristics of the insulating layer.